[A new method to assay urinary oxalic acid using high-performance liquid chromatography]

Area of Science:

• Analytical Chemistry
• Clinical Biochemistry

Context:

• Urinary calculi, particularly calcium oxalate stones, are prevalent, affecting approximately 70% of cases.
• Existing analytical methods for urinary oxalic acid lack suitability for routine clinical application.

Purpose:

• To develop and validate a novel, clinically applicable method for quantifying oxalic acid in urine.
• To establish a reliable assay for routine urinary oxalic acid measurement.

Summary:

• A new method utilizing high-performance liquid chromatography (HPLC) was developed to measure urinary oxalic acid.
• The method involves extraction with tri-n-butyl phosphate and derivatization with 9-anthryldiazomethane (ADAM) for fluorescent detection.
• The assay demonstrated linearity from 1 to 100 µg/ml and showed that healthy adults excrete 23.8 ± 9.0 mg/day.

Impact:

• This accurate, simple, and specific HPLC method facilitates routine clinical measurement of urinary oxalic acid.
• Improved diagnostics for calcium oxalate related urinary calculi.
• Potential for enhanced patient management and prevention strategies for kidney stone disease.